问题
单项选择题
ITU-T目前规定WDM系统各个通路的频率间隔必须为（）。（注：专业性较强没有接触到该类设备）
A.50GHz
B.100GHz
C.80GHz
D.50GHz/100GHz或其整数倍
答案
参考答案：D
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ITU-T目前规定WDM系统各个通路的频率间隔必须为（）。（注：专业性较强没有接触到该类设备）
A.50GHz
B.100GHz
C.80GHz
D.50GHz/100GHz或其整数倍
参考答案：D
| Modern industrial society grants little status to old people. In fact, such a society has a system of built-in obsolescence. There is no formal system for continuing our education throughout our life in order to keep up with rapidly changing knowledge. When our education and job skills have grown obsolete, we are treated exactly like those who have never gained an education or job skills and are not encouraged or given the opportunity to begin anew. As a society becomes more highly developed, the overall status of older people diminishes. Improved health technology creates a large pool of old people, who compete for jobs with the young. However, economic technology lowers the demand for workers and creates new jobs for which the skills of the aged are obsolete, forcing older people into retirement. At the same time, young people are being educated in the new technology and are keeping pace with rapid changes in knowledge. Finally, urbanization creates age-segregated neighborhoods. Because the old live on fixed incomes, they must often live in inferior housing. All these factors -- retirement, obsolete knowledge and skills, inferior standards of living -- lower the status of the aged in society. A century ago, when one could expect to live only to 50 or so, the life span more or less coincided with the occupation and family cycle. But today the average life span allows for fifteen to twenty years of life after these cycles. It appears that our life span is outpacing our usefulness in society. |
The high development of economic technology______.
A．makes job skills out of fashion
B．lowers the demand for workers
C．forces old people into retirement
D．creates new jobs for older people